Already in progress. FAA is working with industry to come up with an unleaded aviation gasoline that will be "drop-in" compatible and replace 100LL. See https

Already in progress. FAA is working with industry to come up with an unleaded aviation gasoline that will be "drop-in" compatible and replace 100LL. See https://www.faa.gov/about/initiatives/avgas/ https://www.faa.gov/about/initiatives/avgas/